In a conventional electric wattmeter, a current detector including a magneto-electric transducer as illustrated in FIG. 1 is used in a current measurement unit (see PTL 1). The current detector includes a conductor 1 to form a looped current path 1b, a magneto-electric transducer 2 provided in the center of the looped current path 1b so as to pass a magnetic flux F therethrough, in which the magnetic flux F is generated by a current to be detected I flowing in the current path 1b, and a ferromagnetic body 3 for collecting the magnetic flux F around the magneto-electric transducer 2.
The configuration of the current detector is simple, and a method of fixing the magneto-electric transducer to the current detector is not complicated. Thus, manufacturing costs can be reduced. The current detector uses the magneto-electric transducer in order to detect current. Therefore, a primary side and a secondary side of the current detector are electrically insulated from each other. Accordingly, the current detector can also function to protect a circuit connected to the secondary side of the current detector.